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pp:class [2021/04/11 14:43] lfa |
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| Now let's check one more interesting concept, Haskell's class system. | Now let's check one more interesting concept, Haskell's class system. | ||
| - | If //data// can be considered the //class// from Java, then ''class'' could be considered the //interface// from Java. | ||
| If you're defining a new //data Point//, you probably encountered some problems trying to print it in GHCI. | If you're defining a new //data Point//, you probably encountered some problems trying to print it in GHCI. | ||
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| As you can see, now we can add our data types in the new class, but also Haskell's types. The only requirement is that the enrolled type must implement our method. | As you can see, now we can add our data types in the new class, but also Haskell's types. The only requirement is that the enrolled type must implement our method. | ||
| - | 5. Create a class ''Contains b a'' that will require a ''contains :: b -> a -> Bool'' method which will return True if ''a'' is in ''b''. | + | 5. Create a class ''Contains b a'' that will require a ''contains :: b -> a -> Bool'' method which will return True if ''a'' is in ''b''. Add ''[a]'', ''List a'' and ''BTree a'' to this class. |
| <note tip>Do we need any additional restrictions for a or b? You can still add restrictions: | <note tip>Do we need any additional restrictions for a or b? You can still add restrictions: | ||
| <code haskell> | <code haskell> | ||
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| </code></note> | </code></note> | ||
| - | 6. Create the ''class Size a'' which will require the methods ''size'' and ''uniqueSize'' | + | 6. Create the ''class Size a'' which will require the methods ''size'' and ''uniqueSize''. Add ''[a]'', ''List a'' and ''BTree a'' to this class. |
| - //size// = the numbers of elements in **a** | - //size// = the numbers of elements in **a** | ||
| - //uniqueSize// = the number of uniqueElements in **a** | - //uniqueSize// = the number of uniqueElements in **a** | ||